The present invention relates to an apparatus and a dosing unit associated with an automatic filling machine for dispensing preset and precise quantities of product into containers, such as bottles, vials, ampoules and the like.
In the pharmaceutical, cosmetic and food fields, it is known to use filling machines for filling different types of dosing devices as a function of the products to be dosed.
In the case of fluid products, volumetric piston pumps, peristaltic pumps, diaphragm pumps, time-pressure dosing systems, flow-meter dosing systems, and mass flowrate meter dosing systems are generally used.
The choice of dosing devices depends on a plurality of factors such as the chemical and physical features of the product to be dosed, dosing volumes, dosing precision and accuracy, and the hygiene and sterility requirements of the filling process. For example, in the case of liquid products that must not come into contact with the pump components, typically to avoid contamination, peristaltic pumps or diaphragm pumps or time-pressure dosing systems are used. In the case of more dense and/or viscous liquid products, piston pumps are preferable.
Filling machines can also be provided with dosing devices for powder or granule products.
The aforementioned dosing devices are driven by a movement mechanism, generally housed inside the filling machine. The movement mechanism provides the required movement, typically a rotational and/or a linear movement, to a dosing device. The dosing device and the movement mechanism are connected by an operating assembly including driving shafts and pistons.
In volumetric piston pumps the dosing device includes a piston driven linearly by the movement mechanism with reciprocating motion inside a dosing chamber so as to draw and subsequently dispense a defined volume of liquid product. In pumps in which the piston also acts as the switching valve, the piston is further rotated by the movement mechanism around the longitudinal axis thereof to make the dosing chamber communicate alternately with a supply conduit and with a delivery conduit.
In pumps in which the piston also acts as the switching valve, the piston is further rotated by the movement mechanism around the longitudinal axis thereof to make the dosing chamber communicate alternately with a supply conduit and with a delivery conduit.
In diaphragm pumps, the dosing device includes an elastic membrane that closes a dosing chamber and is moved linearly with reciprocating motion by the movement mechanism by a driving shaft. In peristaltic pumps, the dosing device includes a rotor that is rotated continuously by a respective driving shaft by the movement mechanism so as to squeeze a flexible tube in which the fluid is located. By squeezing the tube alternately, the fluid advances in the interior thereof.
In dosing devices for powder products, the dosing device includes a dosing drum or wheel rotated with reciprocating motion by the movement mechanism by a respective driving shaft.
The dosing devices are fixed to the filling machines by appropriate supporting structures that also enable connection to the movement mechanism. Known supporting structures ensure precise and solid support for the dosing devices, but entail laborious and complex mounting and dismantling procedures for which specialized operators are required. Such procedures are even more complex and inconvenient if the dosing devices are associated with filling machines operating in an aseptic or sterile environment and thus provided with a sealed housing which enable the processing zone in which the product is packed to be accessed only through openings provided with gloves (i.e., gloveports).
As each dosing device requires a specific supporting structure, possible replacements of dosing devices of one type with devices of another type are not generally possible in the same filling machine or are possible only after complicated and long reconfiguration operations.
In order to provide a certain production flexibility, some filling machines are provided with a plurality of different dosing devices that can be selectively used according to the product to be dosed. Such machines are nevertheless very complex and expensive.
One drawback of known dosing devices is the fact that the operating assembly of the dosing device, i.e. the driving shafts and the pistons, once it has been disengaged from the movement mechanism—for example during conveying or during mounting/dismantling of the device—remains unconstrained and is free to move rotationally and/or linearly, thus allowing uncontrolled and undefined movement of the dosing device. In one step of mounting the dosing device on the filling machine, adjusting and/or calibrating steps for the dosing device and/or for the movement mechanism are thus necessary, which procedures are generally very laborious and time-consuming.
In the case of volumetric dosing pumps, once the piston has been detached from the movement mechanism, it may even disengage from and exit the dosing chamber with the risk of becoming damaged or dirty. As the piston has to be maintained manually inside the dosing chamber, the procedures for assembling and dismantling known volumetric dosing pumps are particularly complex and long, requiring the use of at least two specialized operators.